The invention relates to guided missiles and, more precisely, to a method for guiding a missile, applicable during the terminal portion of the flight path; it also relates to a guided missile operating according to this guidance method.
There exists a demand for AIR to GROUND missiles capable of stopping, at relatively large distances, the threat presented by land formations formed more especially by motorized vehicles such as armored vehicles advancing in groups over the terrain. These armored vehicles, by their nature, radiate thermal energy and thus constitute potential targets which may be detected and located by a missile fitted for example with an electro-optical E.O. sensor operating in the IR band of the electromagnetic spectrum. Furthermore, the missile may be provided with a military charge capable of piercing the protecting armor of armored vehicles. It is possible to direct the firing of such a missile towards a group of armored vehicles; however, there remains the problem of supplying, during the terminal portion of the downward trajectory towards the ground, the trajectory corrections for providing impact of a missile on one of the vehicles detected by the EO sensor.
A missile is already known comprising guidance means for correcting, in the terminal phase of the flight path, the possible error between the direction of a target and the direction of impact of the missile on the ground, in free fall. To this end, the base of this missile of the prior art is equipped with a set of fins which impart to the body of the missile a self rotating movement at a substantially constant angular speed about its longitudinal axis. In the head of the missile is disposed an electro-optical EO sensor and, finally, in the middle part of the body a lateral impeller may supply a predetermined thrust force whose direction is normal to the speed vector of the missile. The EO sensor is formed by a plurality of photodetector cells arranged in a ring in a plane perpendicular to the axis of the missile, so as to provide a hollow conical field of view. Thus, the surface of the ground covered by the field of view of the EO sensor is gradually reduced as a function of the decreasing altitude of the trajectory. When the target comes into the field of view of the sensor, its image falls on one of the photodetector cells which determines, in polar coordinates, the position of the target with respect to the orientation of the impeller. The output signal of the EO sensor is used to supply an order for triggering the lateral impeller at the moment when the orientation of this latter is opposite the direction of the detected target.
This missile of a relatively simple prior art construction does not allow the degree of efficiency sought to be attained and, more especially, a probable hit on the target to be obtained. To attain this aim, the guidance method proposed uses a sensor for tracking the target which measures the rotation of the missile-target line of sight.